A tailored dual core-shell magnetic SERS substrate with precise shell-thickness control for trace organophosphorus pesticides residues detection

For addressing the challenges of strong affinity SERS substrate to organophosphorus pesticides (OPs), herein, a rapid water-assisted layer-by-layer heteronuclear growth method was investigated to grow uniform UiO-66 shell with controllable thickness outside the magnetic core and provide abundant defect sites for OPs adsorption. By further assembling the tailored Au@Ag, a highly sensitive SERS substrate Fe3O4-COOH@UiO-66/Au@Ag (FCUAA) was synthesized with a SERS enhancement factor of 2.11 × 107. The substrate's suitability for the actual vegetable samples (cowpeas and peppers) was confirmed under both destructive and non-destructive detection conditions, showing a strong SERS response to fenthion and triazophos, with limits of detection of 1.21 × 10-5 and 2.96 × 10-3 mg/kg in the vegetables under destructive conditions, and 0.13 and 1.39 ng/cm2 for non-destructive detection, respectively. The FCUAA substrate had high SERS performance, effective adsorption capability for OPs, and demonstrated good applicability, thus exhibiting great potential for rapid detection of trace OPs residues in the food industry.

Radiofrequency enhances drug release from responsive nanoflowers for hepatocellular carcinoma therapy

Hepatocellular carcinoma (HCC) is the sixth most common malignant tumor and the third leading cause of cancer death worldwide. Most patients are diagnosed at an advanced stage, and systemic chemotherapy is the preferred treatment modality for advanced HCC. Curcumin (CUR) is a polyphenolic antineoplastic drug with low toxicity obtained from plants. However, its low bioavailability and poor solubility limit its functionality. In this study, radiofrequency- (RF) enhanced responsive nanoflowers (NFs), containing superparamagnetic ferric oxide nanoclusters (Fe3O4 NCs), - CUR layer, - and MnO2 (CUR-Fe@MnO2 NFs), were verified to have a thermal therapeutic effect. Transmission electron microscopy was used to characterize the CUR-Fe@MnO2 NFs, which appeared flower-like with a size of 96.27 nm. The in vitro experimental data showed that RF enhanced the degradation of CUR-Fe@MnO2 NFs to release Mn2+ and CUR. The cytotoxicity test results indicated that after RF heating, the CUR-Fe@MnO2 NFs significantly suppressed HCC cell proliferation. Moreover, CUR-Fe@MnO2 NFs were effective T 1/T 2 contrast agents for molecular magnetic resonance imaging due to the release of Mn2+ and Fe3O4 NCs.

Enhance antimony adsorption from aquatic environment by microwave-assisted prepared Fe3O4 nanospherolites

A novel hierarchically nanostructured magnetite (Fe3O4) was manufactured using microwave-assisted reflux method without surfactants. The nanostructured Fe3O4 is formed via the co-precipitation of Fe(III) and Fe(II), followed by a nanocrystal aggregation-based mechanism. Moreover, the effects of solution pH, contact time, initial Sb concentration, coexisting anions, and recycle numbers on the adsorption of nanostructured Fe3O4 toward Sb were extensively examined in the batch adsorption tests. The results demonstrated that the obtained Fe3O4 exhibited excellent adsorption ability toward Sb with the maximum adsorption capacities of 154.2 and 161.1 mg.g-1 for Sb(III) and Sb(V), respectively. The prepared Fe3O4 could be easily regenerated and reused for adsorption/desorption studies multiple times without compromising the Sb adsorption ability. Further exploration indicated that the oxidation or reduction reactions infrequently occurred during Sb adsorption processes. The proposed hierarchically nanostructured Fe3O4 thus could be potentially used for sustainable and efficient antimony removal.

Microwave-Assisted Solvothermal Synthesis of Nanocrystallite-Derived Magnetite Spheres

The synthesis of magnetic particles triggers the interest of many scientists due to their relevant properties and wide range of applications in the catalysis, nanomedicine, biosensing and magnetic separation fields. A fast synthesis of iron oxide magnetic particles using an eco-friendly and facile microwave-assisted solvothermal method is presented in this study. Submicron Fe3O4 spheres were prepared using FeCl3 as an iron source, ethylene glycol as a solvent and reductor and sodium acetate as a precipitating and nucleating agent. The influence of the presence of polyethylene glycol as an additional reductor and heat absorbent was also evaluated. We reduce the synthesis time to 1 min by increasing the reaction temperature using the microwave-assisted solvothermal synthesis method under pressure or by adding PEG at lower temperatures. The obtained magnetite spheres are 200-300 nm in size and are composed of 10-30 nm sized crystallites. The synthesized particles were investigated using the XRD, TGA, pulsed-field magnetometry, Raman and FTIR methods. It was determined that adding PEG results in spheres with mixed magnetite and maghemite compositions, and the synthesis time increases the size of the crystallites. The presented results provide insights into the microwave-assisted solvothermal synthesis method and ensure a fast route to obtaining spherical magnetic particles composed of different sized nanocrystallites.

Dual-Targeted Fe₃O₄@MnO₂ Nanoflowers for Magnetic Resonance Imaging-Guided Photothermal-Enhanced Chemodynamic/Chemotherapy for Tumor

The construction of high-efficiency tumor theranostic platform will be of great interest in the treatment of cancer patients; however, significant challenges are associated with developing such a platform. In this study, we developed high-efficiency nanotheranostic agent based on ferroferric oxide, manganese dioxide, hyaluronic acid and doxorubicin (FMDH-D NPs) for dual targeting and imaging guided synergetic photothermal-enhanced chemodynamic/chemotherapy for cancer, which improved the specific uptake of drugs at tumor site by the dual action of CD44 ligand hyaluronic acid and magnetic nanoparticles guided by magnetic force. Under the acidic microenvironment of cancer cells, FMDH-D could be decomposed into Mn²⁺ and Fe²⁺ to generate •OH radicals by triggering a Fenton-like reaction and responsively releasing doxorubicin to kill cancer cells. Meanwhile, alleviating tumor hypoxia improved the efficacy of chemotherapy in tumors. The photothermal properties of FMDH generated high temperatures, which further accelerated the generation of reactive oxygen species, and enhanced effects of chemodynamic therapy. Furthermore, FMDH-D NPs proved to be excellent T₁/T₂-weighted magnetic resonance imaging contrast agents for monitoring the tumor location. These results confirmed the considerable potential of FMDH-D NPs in a highly efficient synergistic therapy platform for cancer treatment.

Magnetic targeting of super-paramagnetic iron oxide nanoparticle labeled myogenic-induced adipose-derived stem cells in a rat model of stress urinary incontinence

Cell-based injectable therapy utilizing stem cells is a promising approach for the treatment of stress urinary incontinence (SUI). Applying a magnetically controlled cell delivery approach has enormous potential to enhance cell retention capability within the specified site. To assess the therapeutic efficacy of cellular magnetic targeting, we applied an external magnetic force to target an adipose-derived stem cell based therapy in a rat model of SUI. The results revealed that magnetic attraction of transplanted cells under the magnetic field was generated by cell uptake of superparamagnetic iron oxide nanoparticles in vitro. More importantly, magnetic targeting improved the retention rate of transplanted cells and facilitated the restoration of sphincter structure and function in a rat SUI model according to the results of histological examination and urodynamic testing. Therefore, magnetically guided targeting strategy might be a potential therapy method for treatment of SUI.

Solvothermal Synthesis of Size-Controlled Monodispersed Superparamagnetic Iron Oxide Nanoparticles

Superparamagnetic iron oxide nanoparticles are of great interest in magnetic targeted drug delivery due to their unique properties. In this paper, size-controlled superparamagnetic iron oxide nanoparticles were synthesized in an ethylene glycol/diethylene glycol (EG/DEG) binary solvent system via a facile solvothermal method. X-ray diffraction (XRD), a scanning electron microscope (SEM), and a vibrating sample magnetometer (VSM) were used to confirm that the prepared samples were superparamagnetic Fe 3 O 4 nanospheres. When the V EG / V DEG was varied from 100/0 to 80/20, 60/40, and 40/60, the average diameters of the resulting Fe 3 O 4 nanospheres were approximately 700, 500, 300, and 100 nm, respectively. In addition, the saturation magnetization ( M s ) of Fe 3 O 4 nanoparticles with a size of 100, 300, 500, and 700 nm was 72.14, 75.94, 80.28, and 85.41 emu/g, and the corresponding remanent magnetization ( M r ) was 3.34, 3.97, 3.26, and 4.28 emu/g, respectively. The relevant formation mechanisms of Fe 3 O 4 nanoparticles are proposed at the end. These superparamagnetic Fe 3 O 4 nanoparticles with high saturation magnetization may have use as targeted drug carriers.

Intelligent nanoflowers: a full tumor microenvironment-responsive multimodal cancer theranostic nanoplatform

Although the collaborative therapy of chemotherapy (CT) and photodynamic therapy (PDT) is much more efficient for tumor treatment than monotherapies, premature leakage of drugs from nanocarriers and hypoxia in the tumor microenvironment (TME) result in systemic toxicity and suboptimal therapy efficiency. To overcome these limitations, we developed an intelligent nanoflower composite (termed FHCPC@MnO2) by coating functionalized polyphosphazene on superparamagnetic Fe3O4 nanoclusters and then growing MnO2 nanosheets as an outer shell. The FHCPC@MnO2 nanoflowers with multistage H2O2/pH/GSH-responsive properties could fully exploit TME characteristics, including supernormal glutathione (GSH) levels, low pH and high H2O2, to realize the specific release of drugs in tumors and maximum synergetic therapeutic effects. The MnO2 nanosheets can elevate O2 concentration by catalytic decomposition of H2O2 and can be simultaneously reduced to Mn2+ by overexpressed GSH in the acidic TME. Meanwhile, the inner polyphosphazene containing (bis-(4-hydroxyphenyl)-disulfide) is GSH- and pH-sensitively biodegradable to release the anticancer drug curcumin (CUR) and photosensitizer chlorin e6 (Ce6) in the TME. Therefore, the "triple-responsive" and synergetic strategy simultaneously endows the nanoflowers with specific drug release, relieving hypoxia and the antioxidant capability of the tumor and achieving significant optimization of CT and PDT. In addition, the resulting Mn2+ ions and Fe3O4 core enable in vivo T1/T2 magnetic resonance imaging (MRI), while the released Ce6 can simultaneously provide a fluorescence imaging (FL) function. Unsurprisingly, the intelligent nanoflowers exhibited remarkable multimodal theranostic performance both in vitro and in vivo, suggesting their great potential for precision medicine.

pH/redox dual-stimuli-responsive cross-linked polyphosphazene nanoparticles for multimodal imaging-guided chemo-photodynamic therapy

Multifunctional nanodrugs with the integration of precise diagnostic and effective therapeutic functions have shown great promise in improving the efficacy of cancer therapy. We report herein a simple and effective approach to directly assemble an anticancer drug (curcumin), a photodynamic agent (Ce6) and tumor environment-sensitive molecules into cross-linked polyphosphazene and coat on superparamagnetic Fe3O4 nanoclusters to form discrete nanoparticles (termed as FHCPCe NPs). FHCPCe NPs have high physiological stability and good biocompatibility, and can enhance accumulation in tumor tissue via the enhanced permeability and retention effect. Meanwhile, the FHCPCe NPs exhibit an effective performance of dual-modality magnetic resonance imaging (MRI) due to the Fe3O4 cores and fluorescence imaging (FL) in the xenografted HeLa tumor because of the fluorescence of Ce6. Importantly, under the conditions of supernormal glutathione levels and acidic microenvironment in tumor tissue, curcumin and Ce6 can be effectively released by the degradation of FHCPCe NPs. Therefore, excellent anti-tumor effects both in vitro and in vivo have been achieved by synergistic chemotherapy/photodynamic therapy (CT/PDT) using multifunctional NPs. Our study highlights the promise of developing multifunctional nanomaterials for accurate multimodal imaging-guided highly sensitive therapy of cancer.

Multifunctional Nanoflowers for Simultaneous Multimodal Imaging and High-Sensitivity Chemo-Photothermal Treatment

Liver cancer is currently among the most challenging cancers to diagnose and treat. It is of prime importance to minimize the side effects on healthy tissues and reduce drug resistance for precise diagnoses and effective treatment of liver cancer. Herein, we report a facile but high-yield approach to fabricate a multifunctional nanomaterial through the loading of chitosan and metformin on Mn-doped Fe₃O₄@MoS₂ nanoflowers. Mn-doped Fe₃O₄ cores are used as simultaneous T₁/T₂ magnetic resonance imaging (MRI) agents for sensitive and accurate cancer diagnosis, while MoS₂ nanosheets are used as effective near-infrared photothermal conversion agents for potential photothermal therapy. The surface-functionalized chitosan was able not only to improve the dispersibility of Mn-doped Fe₃O₄@MoS₂ nanoflowers in biofluids and increase their biocompatibility, but also to significantly enhance the photothermal effect. Furthermore, metformin loading led to high suppression and eradication of hepatoma cells when photothermally sensitized, but exhibited negligible effects on normal liver cells. Due to its excellent combination of T₁/T₂ MRI properties with sensitive chemotherapeutic and photothermal effects, our study highlights the promise of developing multifunctional nanomaterials for accurate multimodal imaging-guided, and highly sensitive therapy of liver cancer.

One dimensional hierarchical BiOCl microrods: their synthesis and their photocatalytic performance

One dimensional hierarchical BiOCl microrods are controlled synthesized via hydrothermal method using sodium citrate as structure-agent. These hierarchical BiOCl architectures exhibit outstanding photocatalytic activity for degrading organic dyes and phenol.

Controllable synthesis and photoreduction performance towards Cr(vi) of BiOCl microrods with exposed (110) crystal facets

BiOCl microrod exposed (110) facets was synthesized via a simple hydrothermal method using sodium citrate as capping agent. It exhibits outstanding photoreduction performance towards Cr(vi) at neutral and acid condition.